1. Field of the Invention
The present invention relates to a hard disk drive (HDD) and, more particularly, to an actuator latch apparatus for a HDD, which prevents an actuator from arbitrarily rotating due to an external shock by locking the actuator at a predetermined position when a disk stops rotating.
2. Description of the Related Art
Hard disk drives (HDDs), which store information in computers, reproduce or record data on a disk using a read/write head. In such a HDD, the read/write head functions by being moved to a desired position by an actuator while being lifted above a recording surface of a rotating disk.
In the meantime, if the HDD does not operate, that is, the disk stops rotating, the read/write head is parked off the recording surface of the disk to prevent a collision with the recording surface of the disk. Such head parking systems can be classified into a contact start stop (CSS) system and a ramp loading system. In the CSS system, a parking zone where data is not recorded is formed on an inner circumferential side of the disk and the head is parked in contact with the parking zone. In the ramp loading system, the head is parked on a ramp that is installed outside the disk.
When the head is parked on the parking zone or the ramp, the actuator may arbitrarily rotate due to an external shock or vibration applied to the HDD such that the head is forced out of the parking zone or the ramp and on the recording surface of the disk. In this case, the head comes into contact with the recording surface of the disk, such that the head and the recording surface of the disk may be damaged. Therefore, when the head is parked on the parking zone or the ramp, the actuator must be locked to a predetermined position so that it cannot rotate accidentally. For this purpose, various kinds of actuator latch apparatuses are provided in the HDD.
FIGS. 1A, 1B, and 1C illustrate a conventional inertial latch apparatus in a HDD.
Referring to FIG. 1A, a HDD includes an actuator 10 that moves a read/write head for data reproduction and recording to a desired position on a disk. The actuator 10 includes a swing arm 12, which is pivotably coupled to an actuator pivot 11, a suspension 13, which is installed on a front end portion of the swing arm 12 and elastically biases a slider 14 with the read/write head thereon toward a surface of the disk, and a voice coil motor (VCM), which rotates the swing arm 12. The VCM includes a VCM coil 16, which is coupled to a rear end portion of the swing arm 12, and a magnet 17, which faces the VCM coil 16.
The HDD further includes an inertial latch apparatus 20 that locks the actuator 10 when the read/write head is parked on a ramp 19. The inertial latch apparatus 20 includes a latch lever 21, which pivots around a latch pivot 22 due to inertia, and a notch 26, which is provided on the rear end portion of the swing arm 12 of the actuator 10. A hook 23 is provided on a front end portion of the latch lever 21 and engages with the notch 26. An iron core 24 is installed on a rear end portion of the latch lever 21 such that a magnetic force acts between the iron core 24 and the magnet 17. The latch lever 21 rotates clockwise due to the magnetic force between the iron core 24 and the magnet 17.
The operation of the conventional inertial latch apparatus 20 will now be explained. First, referring to FIG. 1A, if the head mounted on the slider 14 is parked on the ramp 19, the swing arm 12 pivots clockwise around the actuator pivot 11 due to the VCM. Accordingly, the rear end portion of the swing arm 12 contacts the rear end portion of the latch lever 21, such that the latch lever 21 pivots counterclockwise. Subsequently, if the swing arm 12 continuously pivots clockwise, as shown in FIG. 1B, the notch 26 of the swing arm 12 contacts the front end portion of the latch lever 21 that pivots counterclockwise. Accordingly, the swing arm 12 stops pivoting, thereby completely parking the head mounted on the slider 14.
When the head is parked, if a clockwise rotational shock is applied to the HDD, the swing arm 12 and the latch lever 21 pivot counterclockwise due to inertia. Accordingly, the notch 26 of the swing arm 12 is caught by the hook 23 of the latch lever 21, such that the swing arm 12 cannot rotate further. In contrast, if a counterclockwise rotational shock is applied to the HDD, the swing arm 12 and the latch lever 21 rotate clockwise due to inertia, such that the rear end portion of the swing arm 12 collides with the rear end portion of the latch lever 21 due to their clockwise rotation. The swing arm 12 and the latch lever 21 rebound due to the collision, and pivot counterclockwise, respectively. Accordingly, as described above, the notch 26 of the swing arm 12 is caught by the hook 23 of the latch lever 21, such that the swing arm 12 cannot rotate further.
Next, referring to FIG. 1C, to operate the HDD, the head must be moved from the ramp 19 to a recording surface of the disk. To this end, the swing arm 12 pivots counterclockwise due to the VCM. At the same time, the latch lever 21 pivots clockwise due to the magnetic force acting between the magnet 17 and the iron core 24. Accordingly, since the notch 26 of the swing arm 12 is not interfered with by the hook 23 of the latch lever 21, the swing arm 12 pivots counterclockwise without interference by the latch lever 21.
However, in the conventional inertial latch apparatus 20, while the swing arm 12 rotates clockwise to park the head, which is mounted on the slider 14, on the ramp 19, the swing arm 12 contacts the latch lever 21 twice as described above. During the contacts, a considerable shock is applied to the latch lever 21, and a considerable noise is caused due to the shock.
To reduce such a noise, the conventional latch apparatus 20 adopts shock-absorbing pads 28 and 29 installed on contact portions between the latch lever 21 and the swing arm 12. The softer shock-absorbing pads 28 and 29 result in the higher shock-absorbing effect but the less precise operation of the actuator 10. Accordingly, to ensure a precise operation of the actuator 10, relatively hard pads 28 and 29 need to be used. As a result, the conventional latch apparatus 20 has a limitation in reducing a noise using the pads 28 and 29.